Field of the Invention
The present invention relates to the structure of an IC card and a manufacturing method therefore, the IC card being manufactured by integrally molding a multilayer structure and an IC module.
Hitherto, when an IC card of a type which is constituted by an IC module in an opening portion in a card substrate and a boundary portion adhered by an adhesive is manufactured, the adhesive is used only in the opening portion as described below.
FIGS. 9A to 9C illustrate an IC card of the type described above. FIG. 9A is a plan view of the IC card. FIG. 9B is a side cross sectional view of the same and FIG. 9C is an enlarged cross sectional view which illustrates a card substrate 2 of an IC card 1 and IC module 3. Referring to the drawings, the card substrate 2 is a multilayer sheet structure constituted by stacking overlays 21 and 26 as the outer layers which hold core sheets 22, 23, 24 and 25 therebetween. Each of the above-described sheets which form the multilayer structure has a through hole formed in a portion thereof forming an opening portion 8. Furthermore, an adhesive layer 5 is formed on the core sheet 25 which serves as the bottom portion of the opening portion 8, the adhesive layer 5 being disposed on the portion of the core sheet 25 which is in contact with the module 3.
Then, a process for manufacturing the IC card will be described. First, all of the sheets 21 to 26 are stacked up so that the opening portion 8 into which the IC module 3 is placed is formed. After the IC module 3 has been fitted within the above-described opening portion 8, the overall body is heated and pressure is applied while the body is held by a mirror plate. That is, the card substrate of an existing credit card is, as regulated in JIS X6301, structured in such a manner that a multiplicity of hard vinyl chloride sheets are layered, the sheets in the form of a multilayer structure being then heated and pressed so as to be integrally molded, i.e., welded to one another.
FIGS. 10A to 10C illustrate another IC card. An IC module 3a is arranged to have, in vertical cross section a stepped portion. As shown in FIG. 10C which is an enlarged cross sectional view, an opening portion 8a into which the IC module 3a is fitted also has a two-step cross sectional shape and the adhesive layer is divided into two layers (5a and 5b). Other structures and the process for stacking the sheets and integrally molding the stacked structure are the same as those of the structure shown in FIGS. 9A to 9C.
The conventional IC cards of the type described above have been arranged in such a manner that the IC module is fitted within the opening portion formed through the sheets which constitute the card substrate. Therefore, the contour of the IC module and that of the opening portion must have precise dimensional accuracy. In particular, there arises a problem in that the IC module 3a having, as illustrated in FIGS. 10A to 10C, shape cannot easily be fitted into the opening portion 8a formed in the multilayer sheet while maintaining precise accuracy.